Options range from a display of military might to risky covert actions, The New York Times reported Sunday.
A military exercise to illustrate what difficulties Iran might face should it attempt to block shipping lanes in the Strait of Hormuz is scheduled later this month in the Persian Gulf, with dozens of minesweepers and other vessels from 25 Western countries.
To reinforce its abilities, the U.S. is building an anti-missile radar system in Qatar. Combined with systems in Israel and Turkey, Western forces could quickly zero in and shoot down any missiles shot from Iran, military officials say.
The United States used covert action several years ago to slow Iranian development of weapons-grade nuclear energy. Hackers inserted code into programming for nuclear centrifuges that caused the devices to go out of control.
Since then, many of Iran's nuclear sites have been modified to defend against attacks, intelligence experts say.
The various steps being taken, and those under consideration, are designed to buy time for Israel to find alternatives to a strike against Iran's nuclear facilities.
Israeli Prime Minister Binyamin Netanyahu criticized the United States Sunday for being unclear about how far it would allow Iran to go. He urged President Barack Obama to draw a "clear red line" beyond which Iran would not be allowed to develop its nuclear capabilities.
Setting a "red line" could backfire on the United States, some observers say.
Graham Allison, a Harvard expert on nuclear conflict, said the West has set seven "red lines" in the past 18 years, all of which Iran has stepped over.
On Sunday dozens of protesters stood outside the home of Israeli Defense Minister Ehud Barak -- as they have done every night for the past three weeks -- holding lighted candles signifying the number of Israeli lives that might be lost if Israel began a war with Iran, Ynetnews.com reported.
Barak has estimated that 500 troops might die in such a conflict.
"Not a single official says that a strike in Iran would stop it from developing a nuclear weapon," one protester said. "But one thing is certain -- if we attack Iran we will be led to war."